Method for refining hydrocarbon oils



March 9, 1937. E ELLSBERG A 2,073,446

METHOD FOR REFINING HYDROCARBON OILS Filed June l, 1955 5a 57n I 54 M lis:

GO Q1 e Q30 STORAGE G/4 JNI/ENTOR @7 I I K 757 ATTORNEY.

Patented Mar. 9, 1937 `METHOD FOR REFINING HYDROCARBON OILS EdwardEllsberg, Westfield, N. J., assigner, .by mesne assignments, of.three-.fourths 4to Tide Water Associated Oil Company, New York, N. Y.,`a .corporation of Delaware vApplication June 1, 1933, iSerialiNo.673,803

2 Claims.

-Inthe continuous distillation of hydrocarbon foils of relatively 'Wideboiling range, such as crude ipetroleum,for example, and theirfractionation into cuts. ranging 4from light distillates such as 5--gasoline and kerosene L'through progressively -heavier fractions inAthe lubricating oil range Ldown to the Yheaviest residues suitable forcyl- Linder stocks, it isrcommon practice, well known to thoseacquainted with the art, -to heat the oil l0 -tobe-fdistilled to atemperature suilicient to vaiporize 'all the fractions to be made and inad- -ditionfusually to vaporizefpart of the ultimate residue, and thentodischarge the heated oil into -a'iractionating column, refluxing thevapors rising toward the top of the column in the con- 'ventional'mannerwith part of the overhead condensate, which reflux traveling down thecolumn rcondenses on the plates or'trays in the column progressivelyheavier fractions of more or less commercially homogeneous oils.Depending on the number of plates in the column (and its height) fairlyclose Ycut fractions can be withdrawn from appropriate ,plates inthecolumn ,to obtain lhydrocarbon oils of approximately the*characterdesired whilethe jbottom residue may be obtained of a suitableviscosity according Vto the crude being run and the temperature to whichit has been heated. The above operation is customarily carried o utunder .atmosphericpressure or under some degree-.of `vacuum .as lmay bedesired `to suit the hydrocarbon oil-being distilled.

"inasmuch .as ,on each .plate vor tray in the 'fractionating column fromwhich aliquid frac- `tion may .-be withdrawn asa desired product,

' the liquid `is in .approximate equilibrium .with the 'vapors risingthrough it, which vapors of neces- `:sity .comprise mainly vapors oflower boiling range ,than the .liquid :on .the `tray in question, theliquid .Withdrawn-will contain not only hydro- .carbonsiof the`desiredboiling range to give the product wanted, .but-to aslight degreewill containalsofin solution some ofthe liquid of a boil- ,.ing.pointlowersthan that desired in thestr-eam .45 withdrawn,.withthefresult thatthe product obtained will .be inferior lto that.desired inthe upperend of its-distillationcurve, which involves the ashpoint.

The purpose. of this invention is to overcome 50 `these deficiencies andto .produce aproduct of Vhigher .quality continuously -while at the same-time .eliminating `the need Yfor `such extra vsteps @as re-running, bya simple and advantageous process `of removing continuously theundesired 155 minor percentages Aof lower boiling hydrocarbons,

`giving continuously superior quality fractions to any desired` 'degreeof homogeneity.

In this method, `the liquid lfraction to Ibe reduced, being part or allof thev liquid-on the tray from which it is taken, iscontinuously'withdrawn fromcontact with `the oil and'vaporsinthe vIna-incolumn at anv appropriate tray.- or v'lola-te fand'- flo-Ws into avseparate adjacent chamber `where itis subjected vto avacuum of greaterorlesser de- .gree as may -benecessary,the liquid ractionbeing then rata temperature compatible with and equal to its mean boiling point `underthe ,conditions existing ,in the main column. In this chamber `theliquid sprays into space, .or may be cascaded in thin lms over suitablelhaines, or both. Un der the -inuence of the Yvacuum to l.which thefraction is subjected, :andi-n the `.absence of the relatively largequantities of low boiling -vapors which maintained the previousv,.equi-liinfium, --the slight amount of Ilovv boil-ing voil A,in rthevvfraction, being at a-temperature fhigher than its boiling '-point,Acan no lon-germaintain :itsequilibrium in rthe solution, Yand ashesinto Va .vapor .which is remm/edefrom the chamber Vat a ,suitable .pointinthe upper `part of thetchamben 4while theremaining liquid drops -tothe -bottomf .thechamrberand `is continuouslyWithdraw-nas `theiinishedproduct, or a part-'of 4this-liquid:maybe returned .to Vthe maincolurnn:as reux belowthepointzof original withdrawal. Y

Any desired degree of :separationoflight ends from the fractionWithdrawn:from. the fractionating column canbe obtainedby'increasingithe *degree of vacuumapplied tothe separatingoham.- ber,V'whichregulation -is yeasily obtained Vup .toany degree 'approaching alperfect vacuum that ,may Vbe desired byusing a vproperly sized vacuumejec- 'torwith .one or two v'stages as maybenecessa-ry, together with lacondenser ofany Vusual typebetween the -ejector and the chamber, -whendesired, or a conventional vacuumpump, ythough the ejector ispreferredas being simple to in- 1stall and'to regulate.

The vapors withdrawn from .the .vacuum chamber may loe-dischargedtogether .with the exhaust vsteam from1 the jetejector into the columnat a plate vabove that from which. thefliquid was withdrawn, `so thatthe -vapors lproceed up the column to be further'fractionated,whilethesteam mingles with the vapors andthe steam from the moisture in theoriginal oil andrsuch other Asteam y as may have been added below fromotherjets or in the conventional manner; or the .vapors withdrawn arecondensed and the condensate is returned to the column for furtherfractionation.

slight expense.

In like manner, the residual oil remaining in the bottom of thefractionating tower after the whole liquid has been flashed may be drawninto a separate chamber and be similarly treated to obtain residualcylinder stocks of high quality with respect to flash.

The accompanying drawing is a schematic illustration of apparatus forcarrying out the process. Since the fractionating column may be of 5 anyheight and may contain any number of fractionating plates, a portion ofthis column is shown broken out.

The crude or oil to be fractionated is continuously heated to the.requisite temperature in passage through a conventional heater (notshown) and the stream of heated oil and vapors is continuously deliveredthrough pipe 2 into the lower chamber 3 of a main fractionatingapparatus 4, such as a conventional bubble tower or column.

5 All the part of the oil that will vaporize under the conditions isreleased as vapors at this region,

and the unvaporized liquid residue collects in a pool 5 on the bottomwall 6 of the fractionating column proper. The vapors rise upwardthrough 0 the column, passing through vapor openings 'I in the numerousplates 8 and beneath bubble caps 9, in contact with reflux oil whichflows over the plates and through downtake pipes I0, this re,- iiuxliquid being supplied to the upper portion of the column through a linecontaining a pump I2. Steam may be supplied through a line I3 enteringthe lower portion of the fractionating column.

'I'he light distillate vapors, gasoline for eX- ample, which gain thetop of the fractionating column, are taken oi through a vapor line I5and are condensed in a condenser I6. From a chamber I'I the condensateis pumped by a pump I8 through a line I9 to storage. The reflux liquidthat is pumped into the top of the column may be a portion of this lightdistillate.

One or more liquid streams of an intermediate fraction or fractions arewithdrawn from the side of the column at elevations where desired frac-0 tions are to be obtained, depending upon the design of the column andthe character of the oil that is fractionated.

An upper side stream is taken off through a Valved line 20 to aseparating chamber 2| having 5 means for attenuating the stream, suchmeans being represented in this instance by bailles 22.

This stream, which may be kerosene or a light lubricating oil stock,consistent with the relative location of the plate of the fractionatingcolumn 0 from which it is taken, contains in solution a minor proportionof constituents of boiling points below the boiling range of the mainfraction. In

order to remove these detrimental light ends, a

vacuum of an appropriate order is maintained in the chamber 2| thisvacuum being sufficient to overcome the effect of the equilibrium thatexisted between the condensed oil and the large amount of lighter vaporsin contact with each other in the particular portion of thefractionating column. The result is that the light constituents can nolonger remain in solution in the stream and are dashed off in thechamber 2|. The liquid oil freed of these vapors is drawn off from thebottom of the chamber through a line 23, a cooler l 24, a receiver 25and a pump 2B, and is delivered to storage. The comparatively smallamount of vapor disengaged in the chamber and passing oi above isreturned to the fractionating column. For reasons of simplicity and easeof regulation a steam ejector jet pump is preferably utilized as themeans for subjecting the fraction to the vacuum. The vacuum pump,whatever its nature, is connected with the vapor outlet 2 from thechamber 2|. As illustrated, this outlet has a branch 28 containing a jetejector 29, this branch delivering the released vapors back to thefractionating column at a level above that from which the fraction istaken on" through line 29. Another branch 39 contains a condenser 3| anda receiving vessel 32 from which the light oil condensed in thecondenser may be Withdrawn through a pump 33. When the branch 28 is shutolf and the branch 39 is utilized, the vacuum in the chamber 2| iscreated by an ejector or other vacuum pump 34 connected with an outletfrom the space of the receiver 32 occupied principally byincondensibles. Vapors discharged from ejector 34 may be returned to thecolumn, as is the overhead condensate collected in receiver 32. This isillustrated in the drawing by vlved lines 35 and 36 branched,respectively, from the discharge line from the ejector 34 and thedischarge line from the pump 33 and leading back to the fractionatingcolumn.

Instead of withdrawing, for treatment in vacuum chamber 2|, a part onlyof the liquid oil that descends upon the plate of the fractionatingcolumn from which this side stream is taken, which plate may bedesignated 8a, all of the liquid may be drawn oiT from this part of thefractionating column and be injected into the chamber 2|. In that event,part of the treated oil that passes from the lower portion of thischamber is delivered through a line 3'! to the fractionating column 4 ata point beneath the plate- 8a, to serve as reflux on plates below, whilethe remainder of the treated fraction is Withdrawn through line 23,cooler 24, etc., as a product. When operating in this manner, thedowntake pipe IIJ' 1 from the plate 8a may be shut oi, for which purposethis pipe is shown carried outside the shell oi the column and backagain and provided with a Valve 38.

Another side stream of an intermediate fraction is withdrawn from alower portion of the column 4 through a valved line 39, and isattenuated by spraying through a nozzle 4|) projecting into a vacuumseparating chamber 4|, or by filming over baiiles as in chamber 2| orboth. This fraction is heavier than the fraction treated in the chamber2| and may be understood to be a lubricating oil stock. The light endsdissolved in this stream are ashed off in the chamber 4I under theinfluence of the vacuum, and the liquid fraction, freed of theserelatively light hydrocarbons, is withdrawn from the bottom of thechamber, through a line 42, a cooler 43, a receiver 44 and a pump 45, tostorage. The operation is similar to that performed in connection withthe chamber 2|, and the same arrangements for maintaining vacuum on thechamber and for disposing of the released vapors are illustrated. Thevapor outlet 46 of the chamber has two branches, one of which containsan ejector pump 4'! and is designed to return the vapors to the column,while the other branch contains a condenser 48, and receiver 49, to thefree space oi which an ejector pump 5U' is connected and from which theoil condensed from the vapors may be delivered by a pump 5I. Thecondensate discharged from pump 5l is delivered back to thefractionating column through line 53 and vapors removed by the ejector50 may also be returned to the column through line 52, these linescorresponding to the lines 36 and 35 referred to in connection with thetreatment of the first side stream.

Likewise, the entire oW of reflux in the fractionating column may bediverted from the column at the plate 8b and after the flashing off ofits relatively light ends in the vacuum chamber 4l, a part of thistreated oil may be introduced into the fractionating column below theplate 8b t0 serve as the reflux flowing downward over the plates below.The downtake pipe lb of the plate 8b is shown arranged like the downtakeHla of plate 8a so that it may be conveniently provided with a valve 12.

The unvaporized residual oil that is obtained at the base of thefractionating column proper is treated in the same manner as thedistillate side streams. The chamber 'i3 in Which these bottoms arefreed of their relatively low boiling compone-nts is preferably built inas a sub-section of the fractionating column structure, though separatefrom the interior of the fractionating column itself. In like manner,the invention would not be departed from if the vacuum separatingchambers for the distillate side streams were built into the structureof the main column.

The bottoms are withdrawn from the sump of thle chamber 3 through a line54 and are sprayed from a nozzle 55 into the chamber 13,

where baffles 56 may also be provided. The vacuum in this chamberresults from the action of an ejector jet pump 51 in a line 58 leadingfrom the upper part of the chamber 'i3 and arranged to deliver thevapors to the chamber 3.

Again, the vapors from the chamber 13 may be conducted through a line 59to a condenser 60, from which the condensate and uncondensed vaporsenter a. receiver 5I, in which case the vacuum in the chamber 13 isobtained by the action of an ejector '62 connected with the vapor spaceof this receiver. As in the other similar arrangements previouslydescribed, it is easy in this way to obtain a vacuum as high as may berequired with economy of steam for the ejector pump. The vaporsdischarged from the ejector 62 may be delivered from the system, orthrough a line 63 to the chamber 3. Condensate withdrawn from thereceiver 6| by pump 64 may be either delivered from the system orthrough a line 65 to the chamber 3.

The residual oil, from which the vapors have been flashed in chamber 13,is taken off from the bottom of this chamber through a line 61 and ispumped by a pump 68 through a cooler 69 to storage. This material is,for example, a cylinder stock.

It is possible by the herein disclosed method to obtain much higherquality products in each individual fraction than can be obtained byconventional vacuum distillation, or by conventional atmosphericdistillation, without the need of going to two-stage distillation stillsas at present, with a relatively tremendous tower in the vacuum stagerequired to handle huge volumes of vapors under vacuum, inasmuch as hereonly liquids are injected into the vacuum chambers and the vaporshandled in each chamber are slight as regards quantity and volume evenunder vacuum; nor is it necessary as in conventional atmosphericdistillation (even when steam is used) to go to as high temperatures toobtain desirable viscosities and flashes on the bottoms, or high qualityintermediate fractions devoid of undesirable light ends, while the useof large quantities and volumes of steam in the main tower, whetherunder vacuum or atmospheric conditions, is avoided and smaller towersmay be used` with better results.

Operation of the main fractionating column under a degree of Vacuum notbeing excluded in the practice of the herein described process, it is tobe understood that the vacuum to which a fraction is subjected in any ofthe separating or iash chambers must be lower than the vacuum, if any,existing in the main column.

I claim:

1. In continuous fractional distillation of hydrocarbon oils, in whichthe heated material is subjected to reflux fractionation in a column andin which a stream of liquid oil is removed continuously from Contactwith liquid oil and vapors in the fractionating column, the improvementwhich comprises subjecting the removed liquid material, while in a flashchamber and not in contact with steam and with no further fractionatio-nin said chamber, to vacuum created by the ejector action of a steam jet,and returning to the column the material thus released as vapor,together with the exhaust steam from said jet.

2. In continuous fractional distillation of hydrocarbon oils, in Whichthe heated material is subjected to reflux fractionation in a column andin which a stream of liquid oil is removed continuously from contactwith liquid oil and vapors in the fractionating column, the improvementwhich comprises subjecting the removed liquid material, While in a flashchamber and not in contact with steam and with no further fractionationin said chamber, to vacuum created by the action of a steam jet, andreturning the vapors thus released with the steam from said jet to thecolumn at a point above the point of original Withdrawal.

EDWARD ELLSBERG.

